The invention relates in general to a group control for elevators and, in particular, to a control for entering car calls at the floors.
In a group control of the type disclosed in the European Pat. No. B-032,213, the assignments of the cars can be optimized in time. A sum proportional to the lost time of waiting passengers and the lost time of the passengers in the car is calculated by means of a computer in the form of a microprocessor during a scanning cycle of a first scanner device at every floor, whether a floor call is present or not. The sum is based upon the distance between the floor and the car position indicated by a selector, the intermediate stops to be expected within this distance and the momentary car load.
In this case, the car load present at the moment of calculation is corrected in such a manner, that the probable number of entering and exiting passengers, derived from the entering and existing passenger numbers in the past, can be considered at future intermediate stops. This sum of lost time, also called cost of operation, is stored in a cost memory or register. During a cost comparison cycle by means of a second scanner of the scanning device, the operating costs of all elevators are compared to each other by way of a cost comparison device. In each case, an assignment instruction is stored in an assignment register of the elevator with the lowest operating costs, which assignment designates that floor to which the corresponding car has optimally been assigned in time.
The intermediate stops required for the calculation of the operating costs are generated from the entered floor and car calls. Since the floor and car calls are customarily entered by means of call buttons arranged at the floors and in the car respectively, a passenger has to select twice in order to reach a destination. In the case of an occupied car, the access to the car keyboard is often rendered difficult. Under these circumstances, the control device obtains information about the desired destination relatively late, which for this reason cannot be taken into account for the optimization of the assignment.
U.S. Pat. No. 3,374,864 discloses a group control in which the desired floor of destination can be entered at the floor of entry. For this purpose, call buttons for every floor are arranged at the floor, while no call buttons are arranged in the car. The control operates in a manner such that the car destined for a destination floor makes known the floor of destination at the arrival at the floor of entry by an optical indicating device so that passengers who would like to travel to other floors do not erroneously enter. In this group control, the destination floor call entry is not utilized for the timely optimal assignment of a car call, but it is intended to avoid unnecessary travels caused by wrongly entered directional calls and stops, and to prevent unwanted transportation of passengers in the wrong direction. The arrangement of call buttons for every floor at every floor provided in this group control would increase the cost considerably in the case of larger installations with many floors and would also lead to call button placement problems.